Asphalt blowing



Dec. 1,'1953 w. W, KRAFT 2,661,323

ASPHALT BLOWING Filed Nov. 18, 1949 IN VEN TOR.

Patented Dec. 1, 1953 UNITED STATES PATENT OFFICE ASPHALT BLOWING Wheaton W. Kraft, Scarsdale, N. Y., assignor to The Lummus Company, New York, N. Y., a

corporation of Delaware 2 Claims.

This invention relates to a method of obtaining eicient and economical contacting of asphalt with air.

In accordance with present practice, the operation of blowing asphalt with air involves (1) rllling a blowing tank with charge stock, 2) directing air into the bottom of the tank through a sparger, (3) withdrawing air and vapors from the top of the tank, and (4) withdrawing the oxidized asphalt from the lower part of the tank.

Although batch processes, such as this, are simple and easy to operate they are generally undesirable because they are wasteful oi labor, material, and fuel. Due to the ineiiicient circulation of air and asphalt in a standard blowing tank, a quantity of air is required which is very large.

According to my present invention, the operation of oxidizing asphalt is rendered eihcient and economical by the use of air in a closed circuit, so that the air can be utilized not only for a gas lift eirect, but also for a jet effect that tends to establish the necessary Velocity of the flowing mixture and thereby provide for a positive circulation. Water or steam may also beinjected to insure better control and more efcient operation.

Objects and advantages of this invention will become apparent to one skilled in the art when taken in connection with the accompanying drawing in which the gure is a diagrammatic vertical sectional view of a preferred form of apparatus embodying my invention.

The blowing tank II is preferably cylindrical throughout most of its length and may have a dished bottom portion with an enlarged outlet nozzle I3. A valve I5 may be provided in the nozzle I3. In communication with the nozzle I3 is an attenuated external return conduit I6, the upper end of which is connected to the tank II through nozzle I1. This nozzle may also have a suitable valve I9. If desired, the valves I5 and I9 may be flanges of the gure eight variety whereby the ilow may be completely stopped.

At the lower end of return conduit I6, there is provided a pipe extending upwardly through the bottom of the tube and suitable for the introduction of air, steam, or water. Valve 2l controls the quantity of air admitted from pipe 38 to pipe 26 and conduit I6. Suitable means, not shown, may be employed to cover the end of pipe 26 to serve as a distributing outlet.

Asphalt inlet 24 is provided, preferably at a point in the conduit I6 below the air pipe 26. The ilow of asphalt from pipe 44 to pipe 24 is controlled by valve 25. The flow of water from pipe 48 to pipe 24 is controlled by the valve 46. Pipe 28 is a drawoff pipe through which oxidized asphalt may be removed as desired from tank I I, preferably in the lower part of the tank II. Valve 29 controls the now in line 28.

A sparger 30 is located in the lower part of tank I I below the liquid level 34. Air may be admitted to this sparger through pipe 3I and valve 32. Valve 54 controls the steam which may pass to sparger 30 from line 56 and through line 58. A second sparger is located near thek top of tank II. Steam may be passed to sparger 60 through line 62 and control valve 64.

Nozzle I'I which is near the tcp of tank II is suciently high to be above the highest desired operating level 34. Above liquid level 34 is a vapor space 35 from which vapors may be removed through vapor outlet 36.

In operation, asphalt at a temperature of from about 400 F. to 450 F. is admitted to a lower point in external return conduit I6 through pipes 44 and 24. Valve 25 controls the flow of asphalt.

Simultaneously air is admitted to conduit I8 at a higher point as through lines 38 and 26 under the control of valve 21. The relatively large amount of air in conduit I6 insures a high mixing velocity in the conduit. This produces a desirable mixing effect which insures eicient contact and reaction of the air with the asphalt and the liberation of lighter gaseous material.

From nozzle Il, the mixture is discharged laterally and downwardly into vapor space 35. This further produces an efficient contacting action and added turbulence which enables the asphalt and air to become completely mixed. It also permits any light gases or vapors present to be ejected from the bulk of the liquid. This effect may be aided by means of a. baille, not shown, placed in the path of the fluid as it emerges from the nozzle I l.

Simultaneously with the admission of the asphalt to tank II, air is passed to sparger 30 from line 3| under the control of valve 32. Thus the liquid in tank II will be continually contacted with air. Stripping steam may be admitted as desired to sparger 30 through line 56 under the control of valve 54. Asphalt is passed into tank II until a liquid level 34 is reached and then valve 25 is closed stopping the now of asphalt.

Due to the excellent oxidation conditions in tank I I, it is necessary to have a positive control. Steam is passed into tank II through pipe 62 and sparger 60 thus diluting the oxygen content of the vapor space and thereby minimizing the possibility of re hazards or explosion.

When tank II has been lled to level 34, a

run is started which may continue for a period of time of from 3 to 48 hours. Six hours is about average. During this run, a level of asphalt is maintained at 34, air is admitted through pipes 38 and 3|, and steam through pipe 52. Stripping steam is admitted from line 56. Vapors are removed through pipe 36. Thus a continuous circulation of asphalt is maintained from tank il, through nozzle I3, valve I5, conduit I6, valve I9, and nozzle I1. In this manner a very eiiicient contacting of air and asphalt may be had.

The oxidation of lasphalt is an exothermic reaction and accordingly the temperature rises during the blowing. It is permitted to rise to a maximum which is generally not less than 518 F. nor more than 572 F. If there is a tendency to exceed this maximum, the supply of air may be temporarily decreased or stopped altogether.

The vapors leave tank Il through pipe 3S. When the run is complete, the blown asphalt may be removed through line 28.

Whereas it is contemplated that this process will normally be a batch operation, it is possible to effect a continuous oper-ation by the simple expedient of continuously feeding fresh asphalt in through line 44 and withdrawing the blown product through line 23.

The vigorous mixing and contacting makes it possible to obtain a very high Contact efficiency and accordingly a minimum amount of air will have to be used. This insures that the oxidation will occur in the shortest possible time and at the lowest cost.

, As will be seen, my method oi blowing asphalt has several advantages. It is eficient and. economical with reference to both initial and operating costs, and repairs and maintenance expenses. There is a minimum of internal parts. The method, further, is equally usefulfor a batch, semi-continuous, or continuous operation. It has the advantage of utilizing the air present for two distinct functions, rendering both more efficient.

In operation of this system it has been found desirable to blow the asphalt at a temperature of about 518 F. to about 572 F. The temperature and duration of the blowing process depend on the desired quality of asphalt product. The higher the temperature and the longer the duration of the blowing process, the higher the liquification point and the hardness, and the lower the penetration. rFhese are due to the chemical changes occurring in the asphalt during blowing and include cracking, polymerization, and condensation.

When asphalt is blown under conditions as hereinbefore described, the time of blowing will range from 3 hours to about 48 hours depending on the charge stock and the product desired. Average time is about six hours. It is found that an asphalt can be produced in this manner having a penetration of 10-1GO as determined by ASTM test D5-25, .a softening point of from 200 F. to 125 F., as determined by the ball and ring test, ASTM test DSG-26, and a minimum specific gravity of from 1.01 to 1.05 as determined by ASTM tests D7D-2'7 or 1371-27.

It will be appreciated that there is practically no uniformity of materials which are ordinarily available for the manufacture of asphalt. Not only do the crude oils in different localities differ markedly in their composition and properties, but also rening practices in the removal of the lighter fractions of gasoline, naphtha, kerosene, etc. differ to a great extent, so that the residues available for conversion into asphalts diier widely in composition. It is a feature of this invention that it is adapted to meet substantially all of these varying conditions in a simple and economical manner to produce uniformly satisfactory products.

It will be understood that the word oxidize isl herein used to cover those changes in the asphalt which occur under the conditions described. It will include cracking, polymerization, condensation and distillation, as well as oxidation in the strict sense of the word.

Having thus fully described and explained my invention, what I claim and desire to obtain by Letters Patent is:

1. The method of oxidizing a hydrocarbon residue to produce a blown asphalt of a predetermined degree of oxidation in a closed vertical vessel having an external attenuated circulation conduit including a substantially vertical portion, which comprises, introducing a hydrocarbon residue into the external conduit at a point near the bottom of the vertical vessel in a direction of iiow away from the bottom of the vessel, introducing steam and oxidizing gas into the lower part of the vertical vessel to oxidize the major portion of the hydrocarbon residue therein and drive oi volatile components therefrom, introducing an oxidizing gas into the hydrocarbon residue in the lower part of said vertical portion of the external conduit downstream of the point of introduction of the hydrocarbon residue and in a direction of flow away from the bottom of the vessel so as to simultaneously create a density difference between the hydrocarbon residue in the Vertical vessel and in the external conduit by reducing the density of the residue in the vertical portion of the external conduit, oxidizing the hydrocarbon residue in the external conduit at its reduced density, establishing circulation of the residue in the vessel and in 'the conduit by the density difference created, spray discharging the oxidized hydrocarbon residue from the external conduit into the vertical vessel above the liquid level therein to facilitate removal of light components from the discharge, withdrawing said light components from the top of said vessel separately withdrawing blown asphalt product.

2. The method of oxidizing a hydrocarbon res- I idue to produce a blown asphalt of a predetermined degree of oxidation in a closed vertical vessel having an external attenuated circulation conduit including a substantially vertical portion, which comprises, introducing a hydrocarbon residue into the external conduit at a point near the bottom of the vertical vessel in a direction of flow away from the bottom of the vessel, introducing steam and oxidizing gas into the lower part of the vertical vessel to oxidize the major portion of the hydrocarbon residue therein and drive off volatile components therefrom, maintaining the hydrocarbon residue in the vessel at a temperature of between 518 F. and 572 F., introducing an oxidizing gas into the hydrocarbon residue in the lower part of said vertical portion of the external conduit downstream of the point of introduction of the hydrocarbon residue and in a direction of flow away from the bottom of the vessel so as to simultaneously create a density difference between the hydrocarbon residue in the vessel and the hydrocarbon residue in the external conduit by reducing the density of the residue in the external conduit, oxidizing the hydrocarbon residue in the external conduit at its reduced density, establishing cir- 5 oulation of the residue in the vessel and in the conduit by the density difference created, spray discharging the oxidized hydrocarbon residue 'from the external conduit into the vertical Vessel above the liquid level therein to facilitate re- 5 moval of light components from the discharge, diluting with steam the free oxygen content of the vapors present in the upper part of the vertical vessel, withdrawing said light components from the top of said vessel and separately with- 10 drawing blown asphalt product.

WHEATON WV. KRAFT.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date Kirschbraun Mai'. 21, 1933 Gard et al Apr. 3, 1934 McConnell Dec. 4, 1934 Aldridge Jan. 22, 1935 Heuscher Oct. 5, 1937 Webb Jan. 25, 1938 Subkow Sept. 12, 1939 Aldridge July 14, 1942 Kraft Apr. 1, 1952 

1. THE METHOD OF OXIDIZING A HYDROCARBON RESIDUE TO PRODUCE A BLOW ASPHALT OF A PREDETERMINED DEGREE OF OXIDATION IN A CLOSED VERTICAL VESSEL HAVING AN EXTERNAL ATTENUATED CIRCULATION CONDUIT INCLUDING A SUBSTANTIALLY VERTICAL PORTION, WHICH COMPRISES, INTRODUCING A HYDROCARBON RESIDUE INTO THE EXTERNAL CONDUIT AT A POINT NEAR THE BOTTOM OF THE VERTICAL VESSEL IN A DIRECTION OF FLOW AWAY FROM THE BOTTOM OF THE VESSEL, INTRODUCING STEAM AND OXIDIZING GAS INTO THE LOWER PART OF THE VERTICAL VESSEL TO OXIDIZE THE MAJOR PORTION OF THE HYDROCARBON RESIDUE THEREIN AND DRIVE OFF VOLATILE COMPONENTS THEREFROM, INTRODUCING AN OXIDIZING GAS INTO THE HYDROCARBON RESIDUE IN THE LOWER PART OF SAID VERTICAL PORTION OF THE EXTERNAL CONDUIT DOWNSTREAM OF THE POINT OF INTRODUCTION OF THE HYDROCARBON RESIDUE AND IN A DIRECTION OF FLOW AWAY FROM THE BOTTOM OF THE VESSEL SO AS TO SIMULTANEOUSLY CREATE A DENSITY DIFFERENCE BETWEEN THE HYDROCARBON RESIDUE IN THE VERTICAL VESSEL AND IN THE EXTERNAL CONDUIT BY REDUCING THE DENSITY OF THE RESIDUE IN THE VERTICL PORTION OF THE EXTERNAL CONDUIT, OXIDIZING THE HYDROCARBON RESIDUE IN THE EXTERNAL CONDUIT AT ITS REDUCED DENSITY, ESTABLISHING CIRCULATION OF THE RESIDUE IN THE VESSEL AND IN THE CONDUIT BY THE DENSITY DIFFERENCE CREATED, SPRAY DISCHARGING THE OXIDIZED HYDROCARBON RESIDUE FROM THE EXTERNAL CONDUIT INTO THE VERTICAL VESSEL ABOVE THE LIQUID LEVEL THEREIN TO FACILITATE REMOVAL OF LIGHT COMPONENTS FROM THE DISCHARGE, WITHDRAWING SAID LIGHT COMPONENTS FROM THE TOP OF SAID VESSEL AND SEPARATELY WITHDRAWING BLOWN ASPHALT PRODUCT. 